The Callithumpian Consort is at work again at 8:30 pm tomorrow night at NEC’s Jordan Hall in a slightly premature celebration of the 80th anniversary of Earle Brown’s birth (it’s actually December 26).

They’ll be playing Brown’s Sign Sounds, a rarely heard masterpiece of open form from that resides somewhere on the frontier between serialism and improvisation. They will perform the piece several times, and have assured us that no two performances will be alike.

And they’ll also be continuing their exploration of Alvin Lucier with his Ever Present, for saxophone, flute, piano, and sine waves (which they describe it as “infinitely slow expansion of the music between your ears”) and John Luther Adams’s songbirdsongs, a JLA masterwork from the 1970s.

The Callithumpian Consort has just recorded the complete songbirdsongs under the direction of the composer. Watch for the CD release.

The Callithumpian Consort will playing (with our minds) at 8 p.m. — not 8:30 p.m — on Tuesday the 10th at NEC.

Why does 8:30 have a sort of nostalgic retro sound to it? It’s because, children, long long ago most concerts at night used to begin at 8:30. See “Humoresque” (Jean Negulesco, 1946) with Joan Crawford and John Garfield for documentation.